Evaluation of biological activity of bone morphogenetic proteins on exposure to commonly used electrospinning solvents

Bone tissue engineering is one of the emerging strategies for developing functionally viable bone substitutes. The recent trend in bone tissue engineering is to combine the benefits of a three-dimensional nanofibrous scaffold with biologically active molecules and responsive stem cells. Electrospinning is the most versatile of the scaffold fabrication strategies and may involve the use of an organic solvent at one stage or another. In spite of all distinct advantages of electrospinning, valid concerns about potentially denaturing interactions between the organic solvent and the biomolecules exist. Efforts are ongoing to incorporate osteoinductive molecules, such as bone morphogenetic proteins (BMPs), during the electrospinning process. The challenge lies in ensuring that the biological activity of these incorporated molecules survives the process. This study was specifically designed to investigate the effects of exposure to commonly used organic solvents on heterodimeric BMP-2/7 using slot-blot assay quantified by infrared imaging and on embryonic myoblasts stably transfected with BMP-specific response element linked to a luciferase reporter - C2C12BRA. Overall, the biological activity of these molecules significantly decreased when exposed to organic solvents but can be restored to their original values by increasing the polarity of the solvent. It was found that an aqueous buffer can effectively overcome the deleterious effects of organic solvents on BMPs, thus generating osteoinductive bone scaffolds.